SITES Gives Designers Insight Into Best Dam
Design

The 50-acre
Agricultural Research Service
Hydraulic Engineering Research Laboratory in Stillwater, Okla., has been
long recognized worldwide for modeling, designing and engineering hydraulic
structures for agriculture. Now the lab is set to play one of its greatest
roles--assisting in the rehabilitation and revitalization of thousands of U.S.
earthen dams.

America's countryside is dotted with small dams. Unlike those along rivers,
these dams protect the nation's watersheds. Many serve as municipal water
supplies. They also prevent floods; provide water for irrigation, recreation,
fish and wildlife habitats and groundwater recharge; and improve water quality.
Annually, these watersheds provide Americans with more than $800 million in
benefits.

According to ARS hydraulic engineer
Darrel M. Temple, many of the 10,000 flood- control structures, constructed
with the assistance of USDA, were designed
to have a 50-year service life. About two-thirds were designed before 1962 to
protect communities and rural lands.

Today, many of the dams are in urgent need of revitalization and
rehabilitation. Many no longer work as efficiently as they should. Over the
next 10 years, more than 1,000 will need significant repairs and modification.

To rehabilitate these dams, USDA's Natural Resources Conservation Service
will need to rely on ARS's current research, expertise and the database amassed
by scientists at the Stillwater laboratory over 60 years. The two agencies are
cooperatively developing both technologies for rehabilitating and revitalizing
the dams and software to apply the technologies to engineering problems--called
SITES (not an acronym).

SITES combines the principles of geology, hydrology, soil science and
physics to predict the performance of spillways. The software predicts how an
earthen spillway will perform and evaluates its potential for failure. Future
versions will incorporate current research to predict the damage that results
from embankment overtopping.